Weighing scale



Feb. 8, 1944. H. o. HEM 2,341,216

WEIGHING SCALE Filed July 9, 1940 5 Sheets-Sheet 1 Ha/mr 0. Hem

ATTORNEYS Feb. 8,1944. 7 "H. .0. HEM 2,341,216-

WEIGHING scans Filed July 9, 1940 5 Sheets-Sheet 2.

ATTORNEYS Feb. 8, H. HEM WEIGHING SCALE Filed July 9, 1940 5 Sheets-Sheet 5 Hay/Vol" 0 Hem .38 3 32 INVENTOR ATTORNEYS I Patented Feb. 8, 1944 WEIGHING scam.

Halvor 0. Hem, Toledo, Ohio, assignor to Toledo Scale Company, Toledo, Ohio, a corporation of New Jersey Application July- 9,1940, Serial ,NO. 344,555

9 Claims.

This invention relates to force measuring devices, and more particularly to force measuring devices in the form of weighing scales espe-- cially adapted to determine the compressivestrength of helical springs.

The smoothness of operation of an internal combustion engine depends in a large measure on the-condition of balance of its movablemembers. Accordingly crank shafts, connecting rods, pistons and other rotating and/or reciprocating parts are carefully conditioned and selected. In addition to the balancing of the rotating and reciprocating parts, it was found that valve springs also effect the operation of the machine. This has led to the sorting of valve springs so that all springs in one motor have the same compressive strength. Self-indicating weighing scales of ordinary type, equipped with'means for supporting and compressing the springs, are employed for this purpose. Although such scales are well adapted to' determine and indicate the weight of articles within prescribed tolerances they are not well adapted to indicate very small variations in the compressive strength ofsprings; This requires-the aid of an indicator which travels through a substantially large angle for avery small force increment.

The principal objectv of the present invention is therefore the provision of an improved spring testing device.

A further object is the provision of improved means in a device of the class described whereby a relatively small variation of force, results in a relatively large movement; of the indicator.

Another object is the provision of improved force offsetting means.

Another object is the provision of improved means for changing the force counterbalancing capacty of the device; and

Still another object is'the provision of improved actuating means.

These, and other objects and advantages will be apparent from the following description in which reference is had to the accompanying drawings, illustrating preferred embodiments of the invention and in which similar. reference numerals refer to similar parts throughout the several views.

In the drawings:

Fig, I is a side levationalview of the device.

Fig. II is an enlarged front elevational view of the force counterbalancing' and force indicating means, portions of casing members being broken away for clarity.

Fig. III is an enlarged fragmentary planview as seen from the line III'-III of Fig. IV.

Fig. IV is a front elevational View ofthe spring compressing means partly sectioned along the line IV-IV of Fig. VII.

Fig. V is an elevational .view in section of the. force counterbalancing means.

Fig. VI is a fragmentary side elevation showing a detail of the capacity varying means.

Fig. VII. is an enlarged side elevational view sectioned substantially along the line -VIIVII of.

lever 24.

Fig. VIII is. a sectional plan view substantially. along the line VIIIVII.I of Fig. IV. v

Fig. IX is a plan view of the lever system, housing members being broken away and others. being sectioned,

Fig. X is. anenlarged sectional view along the line X-X of Fig. IX; and, v

Fig. XI isan enlarged sectional view along the line XI:XI of Fig. IX.

Referring to the drawings in detail:

The device comprises a supporting frame [5 surmounted by a base lfi upon which are, erected the spring compressing means [1, forcecounterbalancing, means I8 and force indicating means IS.

The base comprises an L.-shaped box-dike structure (Figures II, VII and IX). Arising from r the. bottom of this base are a pair of integrally cast upwardly extending posts 20 providedwith V-grooved bearings in their upper ends for supporting thereon fulcrum pivots 2| of a two-armed lever 22. The rearward ends of these arms are bifurcated and the aforementioned pivots 2| ex.- tend across the bifurcations; In' spaced relation to these fulcrum pivots and also extending across the. bifurcations is a pair of load' pivots 23 whose edges are upwardly directed. For the purpose of pivotally' supporting a second lever 24, another pair of upwardly extending integral posts 25 are provided which are positioned between the arms of the lever 22. These posts are also equipped withv bearings in their upper ends and support the edges machined on the ends of a pivot member 26 which extends transversely through the This lever is provided with a single load pivot 21 which extends across a bifurcated portion and similarly to the load pivots'23 in th lever 22 is upwardly directed.

The free, or nose end of each of the arms of the lever 22 is also provided with openings 28 through which nose pivots 29 project. The pivots 29, which are downwardly directed, engage V grooves in bearings 3i) mounted between spaced arms 3| on the ends of a yoke-like equalizer 32. The lever 24 has a forked nose portion opening 33 in which a downwardly directed pivot 34 is mounted; This pivot engages the V of a bearing 35 mounted between spaced arms 36 which extends parallelly to the arms 31 of the yoke Bland which are positioned centrally on the yoke 32 between the arms 31 Extending transversely through the bodyof the equalizer yoke 32 and secured therein, directlybelow the bearing 35, is a pivot 31 having downwardly directed knife edges machined on the ends extending on each side of the yoke 32. This pivot extendsat an angle of 90 to the apices of the V grooves of the bearings30 and 35. These knife edges engage bearings 38 mounted between forked arms 39 on the lower ends of a pair of connecting links 40 whose upper ends are forked and bifurcated thus forming a plurality of arms 4|, between spaced "pairs .of-whichare mounted V bearings 42 which :en'gageknife edges 43 on the opposite ends of a pivotal member 44 which in its central portion is provided with a V v groove engaging each projecting knife edge of a pivot 45 transversely extending through an extension lever 46. It will be seen that the V groove in the members '44 extends exactly at an angle of 90 to its pivot edges 43. The'two links 40. one of which being positioned on each side of the lever 46, toprevent their displacement, are connected at theirlower ends through a tiebar 41. The'yoke 32, the connecting links 40 in cooperation with the arrangement of the pivots and hearings in the several members form a universally pivotal connection which permits perfect freedom of movement of the levers 22 and 24 and the lever 46 which extends at right angles to the aforementioned levers.

For the purpose of operatively'conneeting the extension lever to force counterbalancing and force indicating means the extension lever 46 is provided with a forked nose 4B in which a power pivot 49 is fixed. This pivot engages a suitable bearing in a stirrup 50 suspended from the lower end ofa connecting rod I whose upper end, by means of a stirrup 52. pivotally engages a pivot 53 inan ang'ularly extending arm 54 of a force counterbalancing pendulum 55. This pendulum, by means 'of a fulcrum pivot 56 extending transversely through its body, is mounted upon bearing's 51 seated in a suitably formed bracket 58 which is secured to the rear wall of a casing 59 of the load indicating means I9.

Toan angularly extending arm 60 of the pendulumi55' is'secured an indicator 6| whose upper end, provided with an index line 62, cooperates otherwise marked on a chart 64 fixedly mounted in the upper 'end of the casing 59. Since it would be too expensive, if not impossible, to reject all springs whose compression when tested'varied slightly from the standard the present device contemplatesthe establishment of slight variations below and above the standard compression. To enable the operator of the device to readily observe whether the spring being tested is within this tolerance, manually set index arms 65 are rotatablymourited upon suitable screws 6'! passing through their hubs and threaded into the rear wall of'the casing 59. The upper ends of these arms are properly shaped and bent forwardly through slots 68 in the chart 64 so that tips "thereof, which may be contrastingly colored, serve as markers; To enable the operator to quickly set these index arms into desired relation to a zero 'indicium 69, which is a part of the series 63 of indicia on the chart 64, the arms -65 are provided with studs I0 which are secured thereto-so that they may swivel about their longitudinal axis. These studs are provided with threaded openings extending therethrough at right" angles to their longitudinal axes for the reheads I2 by means of which the arms 65 may be swiveled about their fulcrums. To prevent st motion and shifting of their position, owing to vibration or similar causes, a helical compression sprin 13 is circumjacently mounted upon each of'the screws and presses against the inner face of the wall of the housing and the stud 10.

The load pivots 23 and 21, in the levers 22 and 24 respectively, serve to support a platter supporting frame 14. This frame has three down- .wardly extending slotted bosses in which V groove base I6 and to these projecting posts is secured, by

means of screws 18, a platter 19. Since this platter is subject toconsiderable wear in the operation of the device it is covered by a plate of hardened steel, the plate 80 being secured to the platter I9 by means of countersunk screws 8 I. Since devices of this kind must be as nearly foolproof as possible, during rapid operation, the platter supporting frame is held against ac cidental disengagement from its supporting pivots by means of three compression springs 82 whose lower ends are seated in counterbores in the frame I4 and whose upper ends engage adjustable heads threaded on rods 83 studded into the bottom of the base I6. Since the pressure exerted by these springs can be accurately adjusted their effect con be included when calibrating the counterbalancing means of the device.

The rear end of the lever 46, for the purpose of stability, is bifurcated and fulcrum pivots 84 are fixed in the spaced arms so that they extend laterally from the lever. Bosses 85 integrally cast on the bottom of the base I6 and extending upwardly therefrom are provided with V groove bearings 86 in their upper ends. These bearings engage the fulcrum pivots 84 and serve to rockingly support the lever 46. Intermediate the pivot 45 and the nose pivot 49 the lever 46 is bifurcated and the opening thus formed is spanned by a power transmission pivot 81 engaging a bearing 88 of a stirrup 89 (Figures V and II). The upper end of this stirrup 89 is provided with a hook-like extension 90 having a knife edge' 9I which engages a V notch whose converging walls have knife-like edges of a small block 92 which is clamped to the lowermost convolution of a helical spring 93. The upper turn of this spring is formed into an obtuse hook 94 and this hook engages a similar hook 95 on the bottom of a similar spring 96. A second hook 91 is formed on the upper end of the spring 96 and this engages a pin 98 extending across a slot 99 in the lower end of an adjustable suspension member I00. The suspension member I00 has a rectangular cross section and is slidingly seated in a rectangular hole in a cap IOI which forms a closure for the upper end of 'a tubular spring housing member I02. That portion of the member I00 which extends beyond the cap I 0| is turned and threaded. By means of a thumb nut I03 and lock nut I04 the vertical position of the member, and thus of the springs 96 and 93 suspended therefrom, may be carefully adjusted and locked in position. The tubular spring housing member I02 is telescopingly mounted on a second tubular housing member I05 in whose outer" surface a coarse screw thread I06 is accurately cut. The bottom of this tubular member I05 is threaded and fastened into a base collar I01 and it is locked therein by means of a screw I08. This base collar is fastened to the base cover 1! in proper position by means of bolts I 09.

In the interior of the tubular member I02, and extending longitudinally therein, are two splines IIII. These splines are brazed'or otherwise rigidly fastened and are adapted to slide in a groove formed by cutting away portions of the thread I06 on the tubular member I65. These grooves and splines cooperate to prevent the member I02 from turning when a collar III, which is threaded on the threads I06, is screwed up or down to raise or lower the tubular housing I02, the lower edge of the tubular member I02 being seated in a shouldered recess II 2 in the collar III. The member I02 is retained in its seat in the collar III by two jaw-like brackets II3 which are secured to the member Hi2 by means of screws I I4, the collar being free to revolve in a groove milled in these brackets. Screws I I5, which are threaded through the jaw-like brackets II3, are adapted to press a plug II6 of relatively soft material such as fiber seated in a counterbore in the bracket I I3 coaxial with the screw I I5 against the periphery of the collar III after adjustment to lock it securely in position. It will be seen that by loosening the screws H5 and turning the collar III the tubular housing member I62 from which the springs 96 and 93 are suspended may be raised or lowered to increase or decrease the extension of these springs thus increasing or decreasing the counterbalancing capacity of the springs.

In the device illustrated the lead of the thread I06 and the tensile strength of the springs are so calculated and designed that extending the force counterbalancing springs 96 and 93 a distance equal to the lead of the thread I66 increases the counterbalancing effect of the springs 25 lbs. The collar I Ii bears a series of graduations II8 to micrometrically indicate the subdivisions of one increment there being a zero or index indicium II1 engraved on the exterior of the member I 82 to cooperate with the series H8.

The counterbalancing effect of the springs is designed to be less than the number of pounds indicated by the position of the collar III and the indicia lit by the amount counterbalanced by the pendulum 55 when the index line 62 is in registration with the zero indicium 69 'lo cated near the center of the chart 64. Thus the counterbalancing effect for which the combina tion is condition is indicated by the setting of the collar III and small departures in excess or deficiency are indicated by the movement of the indicator 6| over the chart 64.

To damp the vibrations of the device a dashpot I I9 mounted in the base is provided, the plunger of this dashpot being pivotally connected to the lever 46.

To apply pressure on the springs being tested the present invention contemplates the provision of hydraulically actuated mechanism. This mechanism comprises an oil reservoir I26, a motor driven pump IZI and conduits I22, I 23 for feeding the fluid to a control valve I24 and. under certain conditions the fluid then passes through a conduit I25 to the upper end of a hydraulic pressure cylinder I26. This pressure cylinder is erected on a shelf-like plate I21 supported by means of four stanchions I22 (Figures VII and IX). These stanchions are studded into suitable bosses on the bottom of the base I6 and extend upwardly through the cover 11. To obtain greater rigidity, they pass snugly through collars I29 whichare, by means of bolts I39, fastened to the cover 11. Erected upon the plate I21 is a frame comprising four posts I 34 and a plate I32 (Figures VII and III). Two of these posts are studded directly into the plate I21 while the forward two first pass through holes in the base member of the pressure cylinder I26 thus serving to bolt this cylinder to the plate I21. The rear of the base of this cylinder is retained by bolts I33. The plate I32 rests upon tenoned shoulders on the posts I3I and securely locked thereto by means of nuts I34. The piston (not shown) of the pressure cylinder I26 has a downwardly projecting extension I35, a tenoned end thereof being threaded through a movable bracket I36 and into a pressure block I31 which thus serves to securely lock the bracket I36 against the shoulder formed by tenoning the end. The bracket I36 has two rearwardly extending ears I38 (Fig. VIII), each of these ears has a flat face and a semicircular groove is machined vertically therein. A cap I39 having a complementary groove is bolted to the face by means of bolts M6. Seated in the circular hole formed by the semicircular grooves is a spool-like brass bushing which is slidingly mounted on two of the stanchions I28. This bracket thus forms a guide for the lower end of the extension I35 of the piston.

The block I31, which during the operation engages the upper end of the spring, is made of high carbon steel and hardened to minimize the wear.

Other ears I38 of this bracket I35 have drilled and tapped holes into which the lower ends of guide posts I4! are threaded. These guide posts extend upwardly through suitable openings in the plates E21 and I32 and the upper ends thereof are bolted, by means of nuts I52, to a tie plate M3. For a purpose, which will hereinafter become clear, a steel bolt [M having a rounded and hardened head is threaded through this tie plate and a thumb nut I threaded on this bolt on the upper side of the tie plate serves to look this bolt in desired position. The plate I32 is provided with a hardened steel plug it seated in a counterbore in its upper surface in a position to engage the hardened end of the bolt I44.

For controlling the operation of the hydraulic pressure means, a bracket I48, fastened to one of the lowermost angles forming the frame I5, forms a fulcrum as at M9 for a lever Ififi which is provided at the forward end with a foot treadle IIiI. This lever is so stationed within the frame that the operator may comfortably engage it with his foot. The rear free end of the lever I56 pivotally engages a clevis I52 secured to the lower end of a connecting rod I53 whose upper end, which is also provided with a clevis I54, pivotally engages as at I55 the free end of a lever I56 which is fulcrurned as at I6? on a bracket I58 which forms a rigid member of the frame I5. Intermediate the pivotal joints I51 and I55 a clevis I59 is pivotally connected to this lever and this clevis has rigidly secured to its upper end an actuating rod I60, projecting upwardly through aligned openings in the bottom. of the base I6 and in the base cover 11. These openings serve to guide the rod I66 during its reciprocating movement. The rod I66 also projects through an opening in an ear 565 of the bracket I36. Collars I62 and I63 are adjustably mounted on the rod I66 below and above the ear I6i of the bracket I36 and are adapted to be engaged by this ear.

The lever I56 is pivotally engaged by the clevis-like end of a valve actuating rod Ittthe upper end of which, through a hinged coupling I65, engages a protruding portion of a piston I66 of the control valve I24. This valve is fixedly positioned to the bracket I56.

The operation of the device is as follows. For example, it is assumed that valve springs are to be selected to have a compressive strength of exactly 100 pounds when compressed at certain exact proportionof their free length. The thumb screws II5, which look the telescoping half of the load counterbalancing spring housing, are loosened and the graduated collar III is turned on the threads I06 cut in the lower half I05 of this housing until its index line H6 is in registration with that graduation marked on the face of the threads I06 which is indicative of this resistance. The pull exerted by the springs 96 and 93 acting through the bearing 08 against the pivot 81 pulls the lever 46 against an adjustable stop I61 positioned on the inner surface of the base cover 11 and directly above the lever 46 adjacent its free end.

After conditioning the counterbalancing springs 96 and 93, in the manner hereinbefore described, to offset the amount that it is desired to load the springs to obtain the desired compression, the steel bolt I44 threaded through the tie plate I43 is then adjusted so that when its rounded head engages the hardened steel plug I46 in the plate I32 the distance between the lower face of the pressure block I31 and the up per face of the platter 19 is such that a spring, such as I (Fig. VII), will be compressed the required proportion of its free length. This is readily accomplished by making a gauge block and grinding it to the required length of the compressed spring placing it on the platter 19 and moving the pressure block I31 downwardly until through the levers 22, 24 and 46 the pendulum 55 is rocked into a position in which the index line 62 on the indicator 6I is in registration with the zero indicium 69 of the series 63 on the chart 64. e As hereinbefore mentioned, it is almost impossible to afterwards select springs which all move the index line 62 exactly into registration with the zero indicium 69 when compressed to the desired height without some little variation. The permissible variation is therefore established and the index arms 65 are rocked about their fulcrums on the screws 61 by turning the thumb nuts 12 until index points III and I12, projecting over the face of the chart 64, are positioned so that the operator can readily determine whether the spring is within this tolerance. The collar I62 on the actuating rod I60 isso positioned on this rod that when the bolt I44 engages the hardened plug I46 the actuating rod I60 has been depressed so that through the lever I56, the connecting rod I53, the lever I50 and the connecting rod I64 has moved the piston I66 of the control valve upwardly to shut off the flow of the fluid through the conduit I25 and has diverted this fluid to flow through a conduit I13 into the bottom of the hydraulic cylinder I26 thus causing the fluid to force the piston in this hydraulic cylinder upwardly until the collar I63, which is now positioned to be engaged by the ear I 6I of the bracket I36, raises the actuating rod and through the aforementioned levers I56 and I50 and connecting rods I53 and I64 positions the piston I66 of the control valve I24 to stop all flow of the fluid through the hydraulic cylinder I26 when the piston in this cylinder is in its upper position.

The operator now places one of the springs I10 on the platter I9 directly below the pressure block I31, by stepping on the treadle I5I (Fig. I), and pressing downwardly the piston I66 in the control valve I 24 through the medium of the connecting rod I64 is positioned so that circulating pressure fluid through the conduits I23 and I25 is forced in the upper portion of the hydraulie cylinder I26 in the manner hereinbefore described and presses the pressure block I31 downwardly against the spring. This spring is now compressed, it absorbs this pressure until this pressure is equal to the resistance of the counterbalaneing springs 96 and 93 and the lever 46, which until this time has been in engagement with the adjustable stop I61, moves downwardly until the head of the screw I44 comes into engagement with the hardened plug I46 and the ear I6I of the bracket I36 has engaged the collar I62 and has moved through the piston I66 of ,the control valve I24 to reverse the flow of the fluid, there being a slight lag in the movement before this reversal takes place and at this time the operator determines the position of the index line 62 in relation to the series of graduations 63 on the chart 64. If this index line is positioned in the space defined by the index points Ill and I12 the spring is according to the desired standard and acceptable. If the index line 62 on the indicator 6| is not within this space then the spring is not according to the standard and must be discarded.

The embodiments of the invention herein shown and described are to be regarded as illustrative only, and it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

Having described the invention, I claim:

1. In a force measuring device, in combination, a lever system, a platter pivotally mounted upon said lever system, a load counterbalancing spring and auxiliary automatic load counterbalancing means each operatively connected to said lever system to counterbalance a force applied on said platter, said load counterbalancing spring being adapted to be initially conditioned to counterbalance the major part of a force of definite magnitude, means for fixing said spring in such condition, means cooperating with said spring for indicating the magnitude of force to be counterbalanced by said spring and auxiliary automatic load counterbalancing means acting together and an indicator connected to said auxiliary automatic load counterbalancing means for indicating minor increments of force in excess or in deficiency of the magnitude for the major part of which said counterbalancing spring is conditioned.

, 2. In a force measuring device, in combination, a lever system, a platter pivotally mounted upon said lever system, counterbalancing spring means operatively connected to said lever system to counterbalance a force applied on said platter, said counterbalancing spring means comprising a lower housing member and an upper housing member, means adjustably secured to the upper housing member for supporting the upper end of a load counterbalancing spring whose lower end pivotally engages said lever system, means on the lower housing member for micrometrically raising and lowering said upper housing member for extending said spring and conditioning said spring to counterbalance a force of definite magnitude, means cooperating with said housing members for indicating such definite magnitude and means for locking said housing members against relative movement.

3. In a force measuring device, in combination, a lever system, a platter pivotally mounted upon said lever system, counterbalancing spring means operatively connected to said lever system to counterbalance a force applied on said platter, said counterbalancing spring means comprising a lower housing member and an upper housing member, means adjustably secured to the upper housing member for supporting the upper end of a. load counterbalancing spring whose lower end pivotally engages said lever system, means on the lower housing member for micrometrically raising and lowering said upper housing member for extending said spring and conditioning said spring to counterbalance a force of definite magnitude, and means for locking said housing members against relative movement, said means for micrometrically raising and lowering said upper housing member including a rotatable member operatively connected to the lower housing member, said rotatable member bearing a series of graduation marks and a series of graduation marks on said lower housing member.

4. In a force measuring device, in combination, a lever system, a platter pivotally mounted upon said lever system, counterbalancing spring means operatively connected to said lever system to counterbalance a force applied on said platter, said counterbalancing spring means comprising an upper tubular housing member and a lower tubular housing member, a thread cut in the outer surface of said lower tubular housing member, a collar adjustably mounted on said thread, said upper tubular housing member being in telescopic relation to said lower tubular housing member and resting upon said collar, a counterbalancing spring suspended from the upper end of said upper tubular housing member, the lower end of said spring pivotally engaging said lever system, said collar being adapted to raise and lower the upper tubular housing member relative to said lower tubular housing member whereby said spring is extended and conditioned to counterbalance a definite amount of force applied on said platter and means for locking said housing members against relative movement.

5. In a force measuring device; in combination, a lever system, a platter pivotally mounted upon said lever system, counterbalancing spring means operatively connected to said lever system to counterbalance a force applied on said platter, said counterbalancing spring means comprising an upper tubular housing member and a lower tubular housing member, a thread cut in the outer surface of said lower tubular housing member, a collar adjustably mounted on said thread, said upper tubular housing member being in telescopic relation to said lower tubular housing member and resting upon said collar, a counterbalancing spring adjustably suspended from the upper end of said upper tubular housing member, the lower end of said spring pivotally engaging said lever system, said collar being adapted to raise and lower the upper tubular housing member relative to said lower tubular housing member whereby said spring is extended and conditioned to counterbalance a definite amount of force applied on said platter and a pendulum load counterbalancing means operatively connected to said lever system for complementing said spring load counterbalancing means.

6. In a force measuring device, in combination,

a lever mechanism, a platter pivotally mounted upon said lever mechanism, counterbalancing spring means operatively connected to said lever mechanism to counterbalance a force applied on said platter, said counterbalancing spring means comprising an upper tubular housing member and a lower tubular housing member, a thread cut in the outer surface of said lower tubular housing member, a collar adjustably mounted on said thread, said upper tubular housing member being in telescopic relation to said lower tubular housing member and resting upon said collar, a series of calibrating marks on said lower tubular housing member, a series of calibrating marks on said collar, a counterbalancing spring suspended in the interior of said tubular housing members from the upper end of said upper tubular housing member, the lower end of said spring pivotally engaging said lever mechanism, said collar being adapted to raise andlower the upper tubular housing member relative to said lower tubular housing member, and said-calibrating marks on said collar and on said lower tubular housing member being adapted to cooperate to micrometrically position the upper tubular housing member whereby said spring is extended and conditioned to counterbalance a definite amount of the force applied on said platter.

7. In a force measuring device as defined in claim 6, means for preventing rotative movement of said upper tubular housing member relative to said lower tubular housing member, said means comprising a groove in one of said members and a spline on the other one of said housing members engaging said groove.

8. In a force measuring device, in combination, a lever system, a platter pivotally mounted upon said lever system, counterbalancing spring means operatively connected to said lever system to counterbalance a force applied on said platter, said counterbalancing spring means comprising an upper tubular housing member and a lower tubular housing member, a thread cut in the outer surface of said lower tubular housing member, a collar adjustably mounted on said thread, said upper tubular housing member being in telescopic relation to said lower tubular housing member and resting upon said collar, a counterbalancing spring suspended from the upper end of said upper tubular housing member, the lower end of said spring pivotally engaging said lever system, said collar being adapted to raise and lower the upper tubular housing member relative to said lower tubular housing member whereby said spring is extended and conditioned to counterbalance a predetermined portion of the force applied on said platter, a pendulum load counterbalancing means operatively connected to said lever system for complementing said spring load counterbalancing means, a graduated chart and ari'index secured to said pendulum for indicating small increments of force in excess or in deficiency of said predetermined portion of the force counterbalanced by said spring counterbalancing means.

9. In a force measuring device as defined in claim 8, means for housing said pendulum, said indicator and said graduated chart comprising a casing, means cooperating with said graduated chart for defining a tolerance range thereon, said means comprising a pair of index points adapted to be positioned along the face of said chart and means extending to the exterior of said casing for positioning said index points.

' HALVOR O. HEM. 

